She disclosed her diagnosis on Tuesday’s edition of the ABC morning show, which she co-anchored from 1980 through 1997. She spoke with “GMA” host Robin Roberts, who has also been treated for breast cancer recently, as has “GMA” co-host Amy Robach.

Lunden said her treatment will include surgery and radiation. She said she’s already started chemotherapy.

She said after the initial shock of the diagnosis, she resolved to learn everything she can about the illness and go into what she called “warrior mode.” She said she expects to make a full recovery.

The 63-year-old Lunden is now a health and wellness advocate. She has written eight books.